Heat exchange method and apparatus



Jan. 3, 1933. D. F. COMSTOCK 9 HEAT EXCHANGE METHOD AND APPARATUS" Original Filed June 14. 1927 J52 van/Z67 v Patented Jan. .3, 1933 UNITED STATE PATENT OFFICE DANIEL F. OOMSTOCK, OI BROOKLINE, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSTGN- I HENTSQTO STATOR REFRIGERATION, INC., A CORPORATION OF DELAWARE HEAT EXCHANGE mmnon AND urnm'rus Application filed June 14, 1927, Serial No. 198,715. Renewed August 28, 1829.

This invention relates to the combination with heat exchange apparatus of means for exhausting a fluid from the apparatus which is lighter than a liquid circulating therein. For example, means of this character is particularly advantageous when ap lied to refrigerating systems of the type isclosed in the copending a plication of Eastman A. Weaver, Serial N b. 733,699, filed August 23, 1924 (now issued as Patent No. 1,761,551), and the co endin application of Lyman F. Whitney, gerial ilo. 159,342, filed January 6,1927 (now issued as Patent No. 1,756,802). In apparatus of this character, gas is likely to find its way into the system from or through the metal walls or joints of the same, aside from any possibility of slight leakage through oints or connections between different parts of the system, and thus the internal pressure of the system may unduly rise. This is particularly objectionable if the 1nternal pressure is low, of the order of atmospheric or lower.

The present invention is designed to collect non-condensable gas of this character and to entrain the same in a stream of the propellent liquid which circulates in the system,

e. g. mercury, the mercury stream taking the gas to a vessel which is open to the atmosphere and permitting the gas to rlse to thesurface of liquid contained in this vessel whereby the gas is given up to the air. Furthermore, this purging means is arranged in conjunction with the remainder of the apparatus'in such a manner that the quantity of refrigerant vapor exhausted from the system, even if there is no gas to be emitted, corresponds to a negligible amount of liquid refrigerant. 4

Further objects and advantages of the invention will be apparent to those skilled in the art upon a reading of the subjoined description and claims in conjunction with the accompanying drawing, in which the figure comprises a diagrammatic view which discloses the improved purging means as applied to a-refrigerating system of the type identified above.

The accompanying drawing exemplifies an application of the invention to a refrigerating system using mercury or the like as a propellent liquid and water or the like as a refrigerant liquid. A system of this char acter comprises a boiler 1 provided with a heating factor 2 such as an electrical resistance e ement. Mercury is vaporized in the boiler 1, rises in ipe 3, and flows outwardly through the aspirator jet 4, ;where there is a large increase in velocity and decrease in the pressure of the mercury vapor stream. Liquid refrigerant is contained in the cooler 5, and refri rant Va or is drawn from the surface of t is liqui through the duct 20, being entrained in the mercury stream which gives up its kinetic energy in the pumping of the refrigerant vapor.

I The mixture of vapors passes into the inclined funnel 6 which is provided with coolso that the refrigerant vapor flows upwardly through passage 22 to refrigerant condenser 7, where condensation of the refrigerant occurs at a temperature below its condensation point.

The condenser 7 comprises a pipe having a general downward inclination. This pipe is arranged to drain condensed refrigerant to the separating chamber 23, into the midportion of which the passage 22 vents. Liquid refrigerant flows to the bottom of chamber 23 and passes downwardly through pipe 8 to cooler 5, this pipe being provided with a suitable liquid trap 2 1 in order to permit difierent pressures in the cooler and the condenser. A drain 2? which comprises a liquid trap 28 is connected to the passage 22, being 9 adapted to permit the ilow of any heavier propellant which may have been carried into the cooler 5 back to the region at the lower end of funnel 6.

In order to permit exhaustion of non-con densable gases from the apparatus, a fluid pipe 16 is connected to the upper end of the condenser and extends downwardly to join the duct 9. This duct is arranged to drain propellant from the lower end of the funnel 6 and from the lower end of the upstanding passage 22, and comprises a U-shaped liquid trap 29, a continuation of which forms an upward bend 10 of inverted int-formation, as shown. Pipe section 10 is of capillary size and pipe 16 joins the up er portion of duct section 10, this iuncture eing designated a. The ca illary tube extends downwardly from this point to the U-shaped tube 11, the shorter leg of which comprises a vessel 31 into which the capillary is adapted to vent fluid. The upper end of this vessel is open to the atmos here.

T e other leg of tube 11 comprises an upstanding pipe which forms an outlet for the propellant from vessel 31 and holds a column 32 of propellant. The upper end of this leg of tube 11 terminates at 15 in a connection with a downwardly inclined pipe 12 which joins a substantiall vertically disposed pipe 13, that is adapte to hold another column of the propellant, designated by numeral 34, and designed to balance the vapor pressure in boiler 1, the juncture of pipes 12 and 13 being desi ated by the numeral 14. The lower portion of pipe 13 forms a liquid trap 45 through which the pro ellant may return to the holler; the outlet the trap being located below the liquid level in boiler 1. Pipe 13 is continued upwardly beyond point 14 to 45 rovide a by-pass 35 connecting with the drain 9 at point I), which is located near the juncture of pipe 9 with the funnel outlet and at a position designed to be always above the liquid level in trap 29 during normal operation.

In the operation of this system, propellent liquid is vaporized in boiler 1 and rises thr u h upstanding pipe 3 to the aspirator jet a t rough which it passes, thereafter entraining refrigerant vapor coming from the cooler through duct 20. The vapor mixture passes into the funnel 6 where condensation of practically all of the propellant may occur, while the refrigerant, which has a lower temperature of condensation, passes up wardly through pipe 22 and chamber 23 to the refrigerant condenser 7 where it condenses. The liquid refrigerant flows down to the bottom of chamber 23 and through pipe 65 8 to cooler 5. The condensed propellant passes down into the drain 9 and into the U-shaped trap 29 thereof. The pipe 16 normally collects any light non-condensable gas which may gather in the system, since such gas will fail to condense in the condenser 7 7G and will be pumped. to the end of the system. if there is no non-condensable gas in the system, substantially nothing but refrigerant vapor will fill the pipe 16.

W hen liquid propellant piles up in the leg of trap 29 adjoining point 5 to a sui'licient eight, it causes the ropellant in the other leg of the trap to ow upwardly through capillary section 10 past the point a where pipe 16 joins tube 10. Since tube 10 is capil- 3G lary, fluid from pipe 16 will be entrained by the liquid as it flows by the point a towards the vessel 31, the liquid in trap 29 preventing flow of theliuid in the opposite direction. This fluid will tend to be compressed as it 35 passes downwardly to open vessel 31. The lighter fluid then rises to the top of the liquid in vessel 31 and is given up to the atmos phere. The height of the liquid in vessel 31 varies in response to variations in the barometric pressure, it being obvious that the weight of the liquid in this leg of tube 11, plus the atmospheric pressure, will balance the pressure of liquid column 32 in the other leg of tube 11 plus the pressure thereabove. 95 This height is determined by the position of oint 15 which defines the upper end of the 'iquid column, and propellant will flow from the top of the column through the drain 12 to the pipe 13 where it forms the liquid column 34 to balance the pressure in boiler 1.

lit is obvious that instead of the vessel 31 venting to the atmospheres as shown in the drawing, it could vent into a closed vessel, the only condition being that said vessel must be large enough so that it will not become full of gas unduly soon.

It will be noted that oint a is somewhat higher than point 15 an that the weight of the fluid column in the capillary tube must substantially balance the weight of the liquid column 32, the difference in height of these columns serving approximately to determine the amount of fluid that is entrained in the propellant as it passes point 0.. The various 11 parts of the system are so arranged that a proper amount of fluid will be entrained at point a in order to exhaust the maximum quantity of non-condensahle gas that may ordinarily appear in the system, taking into 12 consideration the quantity of refrigerant vapor which will be pumped out of the system at the same time. However, even under conditions of no non-condensing gases appearing in the system the amount of this refri 32 erant vapor will be so small as to have a su stantially negligible effect on the quantity of refrigerant lruid in the system even over long periods of time. It is evident that, when for any reason the operation of the system 13 is stopped either by a thermostat or manual- 1y, i. e. in other words the energization of the heating element 2 is" discontinued, the arran ement of the liquid column 32 in relation to t e open vessel 31 does not substantiallyaffect the liquid level in the latter, and furthermore that variations in atmospheric pres-- said duct, a pipe joining said tube, said pipe being adapted to supply non-condensing ases to said duct, whereby gas is entraine by the liquid, a vessel, said capillary tube having a fixed outlet continually in connection with the vessel, said vessel containing liquid exposed to the air whereby gas may rise to the surface of the liquid in the vessel and pass into the atmosphere, 'and "an upstanding outlet pipe connected to said vessel and adapted to receive liquid therefrom to form a liquid column balancing liquid pressure in the vessel and the air pressure thereabove, and means for returning liquid from said column to the duct when the column reaches a predetermined height. p

2. Refrlgerating apparatus of the type subject to the occurrence of non-condensing gases therein, comprising an evaporation cooler containing a volatile refrigerant, a

condenser, a circulating propellent liquid,

means for utilizing the propellant topump vapor from the cooler to the condenser, means for returning the condensed vaporfrom the condenser to the cooler, and means for purging the apparatus of said gases including a capillary tube through which the ropellant flows, a passage between the con enser and the tube, and a gas receiving vessel communicating with said tube at a point subsequent to said juncture with the passage.

3. Refrigerating apparatus of the type subject to the occurrence of non-condensing gas therein, comprising a condenser operating. at relatively low internal pressure and comprising an evaporation cooler containing a volatile refrigerant, a propellent fluid, means for circulating the propellent fluid to pump vapor from the cooler to the condenser, means for returning condensed refrigerant to the cooler and means for removing gas from the condenser, entraining this gas in another part of thepropellent stream and exhausting the same from said-parts of the apparatus.

4. Refrigerating apparatus, of the type emloying low internal pressure and being subect to the occurrence of non-condensing gases therein, comprising an evaporation cooler containing a volatile refrigerant, a propellent fluid, means for circulatlng the propellent fluidthrou h an endless cycle to entrain vapor from t ecooler in one part of the cycle,

means for entraining said gas in the propellent fluid in another part of the cycle, and means for exhausting said gas from said parts of the apparatus, said last-named means permitting continuance of low internal pressure within the apparatus.

5. The method of refrigeration which comprises the evaporation of vapor from the surface of a liquid refrigerant under conditions of relatively low pressure by means of a propellent stream, condensation of the refrigerant and return of the same to the cooler, while concomitantly collecting non-condensing gases which may occur in the system and entraining said gases in the propellent stream and exhausting the same.

6. The method of refrigeration which com v prises the evaporation of vapor from the surface of a liquid refrigerant under conditions of relatively low pressure by means of a propellent stream, condensation of the refrigerant and return of the same to the cooler while concomitantly collecting non-condensing gases which may have leaked into the system and entraining said gases in the propellant, passing the stream of propellant and gas into a body of liquid having its upper surface exposed to the atmosphere whereby 'the gas is given off 'to the atmosphere, and returning the propellant to the point of refrigerant entrainment.

7. Apparatus of the class described comprising a duct, liquid circulating through said duct, said duct comprising successive downwardly,upwardly and downwardly extending portions, whereby the liquid may flow therethrough in successive downward, upward and downward directions, a portion of said duct which includes said last downwardly extending portion being of capillary tion, a uid lighter than said liquid being contained in said pipe, whereby intermittentflow of the liquid past the juncture of the pipe and tube causes entrainment of the fluid by the liquid, a vessel into which said tube vents, the surface of the liquid in said vessel being exposed to the atmosphere, whereby the lighter fluid may rise to the top of the liquid in the vessel and be given up to the atmosphere, and an outlet in said vessel through which the liquid continues upon its circulatory course, said tube, vessel, and outlet being in continuous open communication with each other, whereby the lighter fluid may pass continually from the tube to the top of the liquid in said vessel.

8. A refrigerating system comprising a lary tube forming a part of said duct, a fluid pipe joining said tube, a vessel, said tube having an outlet in the vessel below the size, a ipe joining said capillary tube porduct, liquid circulating in said duct, a capilpoint of its juncture with said pipe, said vessel containing liquid with its surface exposed to the atmosphere at a point above said outlet, an upwardly extending pipe connected with said vessel and adapted to hold a liquid column and means for returning liquid from the top of this column to the duct, whereby fluid from the fluid pipe may be entrained by liquid circulating in said capillary tube, the amount of said fluid entrained being a function of the vertical distance between the juncture of the fluid pipe with the duct and the top of said liquid column.

9. A refrigerating system of the type employing low internal pressures and subject to the occurrence of ROD-COIKlQDSflblQ gases, comprising a refrigerant circuit and a circuit for a less Volatile fluid, said circuits having a part in common where the less volatile fluid imparts energy to the refrigerant fluid, the circuit for the latter including a cooler where refrigeration is effected by evaporation of the refrigerant, the circuit for the less volatile fluid including a heating factor which imparts energy to said fluids to pump the same about their circuits, and

auxiliary pumping means associated with one of the aforesaid circuits and adapted to receive fluid therefrom said pumping means including a duct having a capillary portion, a pipe connected to a portion of the refrigerating system where non-condensing gases are likely to occur and to the capillary portion of the circuit, said duct having an opening exposing the liquid therein to a gas-containing region, whereby fluid circulating through the circuit may entrain non-condensable gases in the capillary tube and emit the same to the vessel.

10. The method of refrigeration which comprises employing a source of energy to effect the circulation of refrigerant about a refrigerant circuit and concomitantly maintaining a low internal pressure within the circuit by circulating a heavier liquid through a circuit which is associated with the refrigerant circuit, directing non-condensable gases from said refrigerant circuit to a portion of the heavy liquid circuit where the gases are entrained by the heavy liquid and separating the gases from the heavier liquid in a subsequent part of its circuit.

11. Refrigerating apparatus including a refrigerant circuit and means associated therewith to cause the circulation of the refrigerant through said circuit, means continually maintaining said circuit at low pressure, comprising a passage connected to a portion of the circuit where non-condensable gases are likely to occur, a circuit for a heavy liquid associated with said refrigerant circuit and having a duct portion of restricted diameter connected to said passage, the heavy liquid in said circuit forming separate liquid globules or pistons in said duct portion wheremesses by non-condensable gases are entrained from said passage, and means for separating the liquid and the entrained gases, whereb the former continues about its circuit and w ereby the latter is exhausted to the atmosphere.

12. In a low-pressure refrigerating system, a refrigerant circuit, a circuit containing another fluid immiscible with the refrigerant purgin means without moving mechanical parts or removing non-condensable gases from the refrigerant circuit, said purging means containing a second fluid, and a heat source for causing circulation of the refrigerant and said second fluid, said purging means including a duct having capillary portion through which the second fluid passes in separate globules, a duct supplying gases from the refrigerant circuit to said capillary portion for entrainment between the globules, a vessel containing a liquid body of said second fluid, said capillary portion having a fixed outlet opening into said vessel so that the globules and entrained gases pass into the liquid body, said vessel having an outlet communicating with a gas containing space above the liquid body in said vessel whereby the entrained gases rise and are exhausted into said space, and an outlet duct with a fixed mouth opening into said vessel through which liquid may continually pass due to energy received from said heat source, whereby the refrigerant circuit may be continuously purged of non-condensable gases without the use of moving mechanical parts.

13. In a low-pressure refrigerating system, a refrigerant circuit, purging means without moving mechanical parts for removing noncondcnsable gases, said purging means comprising a duct through which a relatively heavy fluid circulates, and means causing the flow of refrigerant through its circuit and the flow of the heavv fluid through the duct, said duct including a downwardly extending tube of capillarv dimensions through which theheavy fluid passes in separate liquid globules, means for supplying gases from the refrigerant circuit between the globules, a vessel containing a body of the heavy fluid, the capillary duct portion having I a fixed outlet communicating with said vessel and arranged so that the globules and entrained gases pass into the liquid body, the vessel having a fixed, continuously open outlet to a gas-containing space above the liquid body into which space the gases pass, and an upwardly extending outlet duct in con tinuous open communication with said vessel, through which duct liquid from said vessel passes. a spill-over at the upper end of the outlet duct, a liquid column in said duct, the quantity of gas entrained between the globules being a function of the height of said liquid column and the pressure of the gas above the liquid body being balanced by the pressure of said column.

including a duct havinga downwardly extending capillary portion through which the separate mercury globules ass, a duct supplying gases from the refrigerant circuit to sa1d ca illar portion for entrainment between t e glo ules, a vessel containing a body of liquid mercury, said capillary portlonhaving a fixed outlet opening into said vessel so that the globules and entrained gases pass into the liquid body, said vessel having a fixed, continuously open vent into a gas containing space above the liquid body in said vessel into which the entrained gases rise and are exhausted, and an outlet duct with a fixed mouth openin into said vessel through which mercury mayie continually emitted, whereby the refrigerant circuit may be continuous- 1y purged of non-condensable gases without the use of moving mechanical parts.

15. A low-pressure refrigerating system comprising ducts in continued intercommunicationwith each other, a circulating refrigerant and pressure balancing means comprising liquid columns in said ducts, purging means associated with said s stem to remove non-condensable gases there rom, said purging means containing a relatively heavy liquid, and comprising a downwardly extending capillary duct through which heavy liquid globules pass, means supplying gases from a part of the system to said capi lary duct, a vessel containing a body of the heavy liquid with the surface of the latter exposed to the atmosphere below theupper end of said capillary duct, an upwardly extending outlet duct with a mouth in continuous communication with said vessel and containing a liquid column, the pressure of the atmosphere upon the liquid body being continuously balanced by the fluid pressure in said outlet and capillary duct, and the quantity of gasentrained between the globules being a function of the height of said liquid column.

16. A refrigerating system comprising ducts always in continued open communication with each other, circulating refri erant,

ressure balancing means provided so ely by fluids in the system, and auxiliary pumping means associated with the system, sa1d pumping means including a capillary tube throu h which separate globules of a second-relativefly heavy fluid pass with bodies of other fluid therebetween, said heavy fluid being immiscible with the refri erant, and a heating element causing circu ation of the refrigerant and of the globules through the tube.

- 17. A refrig rating system containing refrigerant an a heavy liquid immiscible therewith and comprising a cooler in which the refrigerant is vaporized, a condenser for condensing the refrigerant vapor, means for circulating refrigerant, means for pumping fluid from one portion of the system to another including a capillary tube through which separate globules of said heavy liquid pass, ducts interconnecting said parts and always open so that the pressure tends to equalize throughout the system, this tendency being-counteracted by columns of liquid in the system to balance pressure. difierences between different parts of the system including the pressures at the opposite ends of'said tube, whereby the pressures throughout the system are balanced without the aid of valves.

18. A low-pressure refrigerating system comprising ducts in continued intercommunication with each other, a circulating refrigerant and pressure balancing means comprising liquid columns in said ducts, auxiliary pumping means associated with said system, said pumping means comprising a downwardly extending capillary duct through which heavy liquid globules pass, means supplying a lighter fluid from a part of the system to said capillary duct, where the lighter fluid is entrained between said globules, a chamber containing. a body of the heavy liquid in direct continued communication with the lower end of said capillary duct, an upwardly extending outlet duct with a mouth in continuous communication with said vessel and containing a column of the heavy fluid, a body of the lighter fluid above the heavy liquid body whereby the li hter fluid may bubble through the body of eavy liquid to the body of lighter fluid, the quantity of fluid entrained between the globules being a function of the height of said liquid column and the pressure of the lighter fluid above the liquid body being continually counteracted by the pressures in said capillary duct and in the outlet duct.

19. A low-pressure refrigerating system comprisin ducts in continued intercommunication wit each other, a circulating refrigerant and pressure balancing means comprising liquid columns in said ducts, auxiliary pumping means associated with said system, and containing mercury, said pumping means comprising a downwardly extending capil- I lary duct through which separate mercury glo ules pass, means supplying 'a lighter fluid from apart of the system to said capillary duct, where the lighter fluid is entrained between said globules, a chamber containing a body of mercury in continuous open communication with the lower end of said capillary duct, an upwardly extending outlet duct with a mouth in continuous communication with said vessel and containing a column of mercury, a body of the lighter fluid above the heavy liquid mercury body whereby the lighter fluid may bubble through the body of 63 Leeeeee Ziquid mercury to the body of lighter fluid, the quantity of fluid entrained between the globules being a function of the height of said liquid column and the ressure of the lighter fluid above the liquid ody being continually counteracted by the pressures in said capillary duct and in the outlet duct, and a single source of energy effective to cause the circulation of said mercury and lighter fluid 13 throughout their respective paths.

Signed by me at Boston, Massachusetts,

this 9th day of June 1927.

DANIEL r. ooMsrooK. 

